I got this error "JAVA_HOME "
When trying to install CDH4 of Cloudera Hadoop standalone version.
Although i did all the needed configuration + echo $JAVA_HOME is fine.
+ writing "java" works + writing "java -version" works ok .
Nothing really helped except
1. go to /etc/hadoop/conf
2. edit hadoop-env.sh
add export JAVA_HOME=/usr/lib/jvm/jdk1.6.0_32
then try again, i was trying to format the namenode.
Hoped it helped.